Liquid biopsy diagnostic developer CellMax Life and single-cell diagnostics company IncellDx announced the two companies will join efforts in developing and marketing circulating tumor cell (CTC) blood tests across multiple solid tumors and indications to provide personalized therapy selection and monitoring.

CellMax Life’s CTC blood test, based on its CMxTM platform, capturing CTCs with a proprietary microfluidic chip with biomimetic coating and custom antibodies, will be combined with IncellDx’s proprietary microfluidic reagents BioINK™ to analyze both protein and/or mRNA expression. BioINK enables highly sensitive and specific quantification of protein or mRNA expression at a single-cell resolution. The first product created under this collaboration is a proprietary blood test to quantify the expression of PD-L1 – a key protein involved in suppressing the immune system – used for immunotherapy selection and monitoring.

There are close to 3,500 active biomarker-driven cancer clinical trials currently recruiting patients, and many of these trials rely solely on tissue-based biomarkers. Unfortunately, tissue tests may be inadequate, putting clinical trials at risk. This is true of tissue testing for PD-L1 expression for immunotherapy selection.

According to Dr. David Gandara, oncologist and director of the Thoracic Oncology Program at University of California, Davis, “PD-L1 can be unevenly distributed in tissue, leading to a false negative, and denying patients the opportunity to receive immunotherapy. Up to 20 percent of PD-L1 negative patients in tissue tests have been known to respond to immunotherapy. Looking into the future, blood-based testing provides a means for repeat testing and timely monitoring, which would not be possible otherwise. A PD-L1 blood test can overcome these issues and would be an attractive alternative to tissue testing.”

Several published studies have demonstrated the utility of CTC PD-L1 tests for immunotherapy monitoring, including a study showing that patients without PD-L1+ CTCs after 6 months of treatment showed a clinical benefit from nivolumab – an immunotherapy used to treat cancer – while patients with PD-L1+ CTCs experienced disease progression.

Performance data of the PD-L1 test in non-small cell lung cancer (NSCLC) will be presented in Chicago at the American Academy of Cancer Research (AACR) Annual Meeting, taking place on April 14 through 18. The test was able to capture CTCs for PD-L1 testing in blood in about 90 percent of patients across all stages of cancer. About 50 percent of the patients tested for CTCs were PD-L1 positive. This is consistent with previously reported PD-L1 positivity rates in clinical studies (Abstract 3653/13).

Dr. Bruce Patterson, CEO and founder of IncellDx said, “Cancer is driven at different levels: DNA, RNA and protein. With CTC-based liquid biopsies, we can analyze all of these analytes simultaneously in intact cells, combining antibodies, quantitative RNA in situ hybridization and DNA cell cycle. This is not possible with most current liquid biopsies that analyze only DNA from lysed cells. CellMax Life’s CTC blood test has unprecedented sensitivity in isolating rare CTCs, which can be readily analyzed by the BioINK platform at the single-cell level. Our joint efforts will lead to reliable diagnostic solutions throughout the patient treatment continuum.”

The tests will be processed at CellMax Life’s CLIA-CAP accredited lab in Sunnyvale, California and will be jointly marketed in the United States by the company’s sales force.

“We are excited to partner with IncellDx, whose highly accurate reagent platform will bring tremendous added value to our tests,” said Atul Sharan, CEO of CellMax Life. “Together with IncellDx, we will be a valuable partner for pharmaceutical clinical trials looking for multi-analyte blood tests for therapy selection and monitoring. The PD-L1 test is just the beginning of what this joint venture will accomplish.”